الفهرس 
الغلاف الانجليزىOnly 14 pages are availabe for public view
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Abstract
An experimental investigation on cyclic variability in a single-cylinder spark- ignition, Ricardo E6/MS variable compression ratio engine fuelled by gasoline and jojoba bio-gasoline blends with jojoba bio-gasoline volumetric fraction of 0%, 5%, 10%, 25%, 50% and 100% was carried out. The effects of engine operating parameters and combustion chamber shape were examined intensively. For each test condition, the in-cylinder pressure data were recorded at each degree of crank angle rotation for a total of two hundred consecutive engine cycles. These pressure-time histories were used for the detailed study of combustion characteristics. For this purpose, a measuring set-up consisting of a piezo-electric pressure transducer with charge amplifier and fast data acquisition card was used. The generalized plot of coefficient of variation in indicated mean effective pressure was demonstrated as an effective means of diagnosing the cyclic variability.
A set of experiments were carried out to cover the effect of the design and operating parameters of the engine on cyclic variations, e.g. engine load, speed, equivalence ratio, compression ratio, inlet air temperature and ignition timing. The experiments revealed that blending gasoline with 5% bio-gasoline had negligible effect on cyclic variability and with increasing the percentage of bio-gasoline, cyclic variations increase. Blends with 10%, 25% and 50% show an increase in cyclic variations compared to pure gasoline but was within an acceptable limit, so the engine can run steadily with such blends without any modifications. However, fuelling the engine with pure jojoba bio-gasoline lead to unstable operation at normal conditions; to run steadily special operating conditions are required and compression ratio of higher than 10 is recommended.
However, the coefficient of variations of indicated mean effective pressure (COVimep) for jojoba bio-gasoline decreases with the increase of compression ratio, engine speed, spark advancing, using slightly rich mixture, raising inlet air temperature and higher loads. The study showed that the fast burning combustion chamber (bowl-in-piston) is superior in reducing the cyclic variability for gasoline and various blends of gasoline and jojoba bio-gasoline.
All the experimental data were used to develop analytical correlations to enable a prediction to be made for use in the design stage.